The primary purpose of this study is to evaluate the efficacy, safety, pharmacokinetics, pharmacodynamics, and immunogenicity of ravulizumab in Chinese adult participants with Acetylcholine receptor (AChR) + Generalized Myasthenia Gravis (gMG).

Inclusion (key)

• Confirmed generalized MG: Diagnosis ≥6 months before screening, anti-AChR antibody positive, and supportive diagnostic evidence (e.g., abnormal SFEMG/RNS or response to anticholinesterase therapy).
• Disease severity: MGFA Class II-IV at screening.
• Symptoms threshold: MG-ADL ≥6 at screening and on Day 1.
• Meningococcal vaccination: Up to date within 3 years or vaccinated before first dose to mitigate risk with complement inhibition.
• Body weight: ≥40 kg.
• Vaccinated against meningococcal infections within the 3 years prior to, or at the time of, initiating study drug.

Exclusion (key)

• Thymic disease:

  • Untreated thymic malignancy/carcinoma/thymoma excluded.
  • Prior thymic malignancy allowed only if treatment completed >5 years, no recurrence in last 5 years, and clear CT/MRI within 6 months.
  • Prior benign thymoma allowed if confirmed benign, treatment >12 months ago, no recurrence in last 12 months, and clear CT/MRI within 6 months; otherwise follow malignancy rules.
  • Thymectomy within the last 12 months

• Infection risk:

  • History of meningococcal disease or unresolved infection, or active systemic infection within 14 days of Day 1 excluded.
  • Persistent/recurrent infections in past 12 months that add risk
  • HIV, active HBV (HBsAg+ or anti-HBc+ with anti-HBs-), or active HCV (unless documented successful treatment/SVR)

• Safety/medical status:

  • Hypersensitivity to study drug components (including murine proteins)
  • Recent hospitalization ≥24 hours within 28 days of screening
  • Substance use disorder per DSM within 12 months.
  • Recent/other malignancy within 5 years (except as above for thymic).

• Prior/Concomitant Therapy

  • Complement inhibitor within < 5 half-lives before Day 1.
  • Human neonatal Fc receptor (FcRn) inhibitor within < 5 half-lives before Day 1.
  • Rituximab, ocrelizumab or other B cell-depleting therapy within ≤ 6 months (180 days) before Day 1.
  • Periodic (chronic) administration of PP/PE, or IVIg as maintenance therapy received or scheduled within ≤ 6 months before Day 1

• Key labs:

  • ALT >2× ULN, direct bilirubin >2× ULN.
  • eGFR <30 mL/min/1.73 m² or on dialysis.
  • Any other clinically significant lab abnormality making participation unsafe.

Note: Other protocol-defined criteria may apply and should be verified during full eligibility review.

Alexion has a public commitment to allow requests for access to study data and will be supplying a protocol, CSR, and plain language summaries.